Effect of pH on the capacitive behavior of microgap sensor

The current study demonstrates the fabrication and electrical characterization of aluminum micro-gap onto polysilicon substrate. Low cost conventional photolithography technique was used to fabricate the aluminum micro-gap. The fabricated device was tested for different pH values. In order to get the micro-gap structure, mask was design using AutoCAD software and due to because of low dimensions the designed mask was transferred on chrome glass to get chrome mask for better resolution. The size of the fabricated micro-gap was around 09μm. It was observed that when the pH value switches from acidic to basic (pH10 to pH6) the capacitance decreased from 290nF to 9nF. The change in capacitance suggested that the fabricated device can differentiate between acidic and basic pH values with marginal changes. Future work will focus to decrease the microgap size until reach to nanogap, such nanogap will be used for biosensing application by inserting biomolecule in between the nanogap.